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(No Model.) 2 SheetsSheet- 1.

' J. J. OA-RTY.

TELEPHONE EXCHANGE APPARATUS.

No. 564,173. Patented July 14, 1896.-

4 I v jffiornay" (No Model.) 2 Sheets-Sheet 2'.

J. J. GARTY. TELEPHONE EXCHANGE APPARATUS.

No.564173. I PatentedJuly14,1896.-

UNITED STATES PAT NT OFFICE.

JOHN J. OARTY, OF NEV YORK, N.Y.

TELEPHONE-EXCHANGE APPARATUS.

SPECIFICATION forming part of Letters Patent No. 564,173, dated July 14,1896.

Application filed November 17, 1887. Serial No. 255,380. (No model.)

To all whom it may concern.-

Be it known that 1, JOHN J. OARTY, a citizen of the United States,residing at New York, in the county of New York and State of New York,have in vented a certain new and useful Improvement inTelephone-Exchange Apparatus, of which the following is a full, clear,concise, and exact description, reference being had to the accompanyingdrawings, forming a part of this specification.

My invention relates to telephone-exchan ge systems and circuits,particularly to such systerns in which metallic circuits are employedbetween the central office and the substations, and has specialreference to certain operations necessary to be performed by thecentral-office operator in communicating with the substation, and viceversa, and in the circuits and apparatus therefor, and may specificallybe stated as, first, improved means for signaling in metallic circuitsbetween the central office and the substations, and vice versa; second,an improved system of central-office testing, whereby an operator at oneboard, in a system of multiple boards, may find out'whether a'line is inuse or not on any other board; third, an improved device for looping theoperators instrument set into the line leading to a subscribers station;fourth, an improved double connector-plug arranged to maintain thecontinuity of that portion of the metallic circuit having thecentral-office-operators instruments in its circuit, when the plug isemployed in the switchboard-socket or at rest on its metal plate; fifth,a metallic circuit both ends of which are in the central office, one endbeing normally open and the other end being connected to ground throughan electrical generator and an annunciator arranged so that whenconnections are made a closed metallic circuit is formed.

To describe my invention in detail, Figure 1 of the drawings illustratesthe connections of a substation-line on three switchboards and theconnecting-sockets on each board in a metallic-circuit central-officemultiple system at the one end, while located at different positions onthe circuit are two substations, as shown. Fig. 2 illustrates thecentral-office operators looping-in metallic-circuit apparatus,consisting of double connecting-plugs,

telephones, looping-in socket and plug, call-,

ing-key, and electric generator. Fig. 3 shows a section of a looping-insocket with a plug inserted. Fig. 4 shows a section of aswitchboard-socket with aconnecting-pluginserted. Fig. 5 represents amodification of the operators circuit-changin g socket. Fig. 6 is adiagram of two metallic circuits connected through the central office.Fig. 7 is a view showing the manner of testing.

In Fig. 1, a, a, and a are the terminal connecting-sockets of aline-circuit, one on each of three boards in the central office. Tl'iesesockets are of the ordinary kind employed on the multiple switchboardsof telephone central offices, composed of a metal body d, having anorifice for the reception of a plug, an insulated contact-screw 6, uponwhich rests normally a spring f. One wire I) of the metallic circuit isconnected to the metal body d, the other wire a of said circuit beingconnected to the tail of the spring f. Both wires b and 0 run to the substation or stations, two being shown, as M and N. I have shown thewires 1) and c as connected to the signal apparatus of each substationonly, the telephones and other apparatus not being shown.

Each signal apparatus is looped into the line, but I show a ground-WireNV and a normally open key K at one side of the apparatus, for a purposeto be hereinafter explained.

The wire 0 leaves the contact-screw e of the socket a, connecting in theline-annunciator An, and goes to ground through battery Ba.

The operators looping-in apparatus is shown in Fig. 2, of which P and Pare double connecting-plugs composed of a body of insulating substancet', a central metal plug j, surrounded by butinsulated from the tubularplug Z on one end, with wires 0 and b extending from the plugs j and Zthrough the body to two metal plates 0 and p at the opposite end of theplug and to the binding-posts r and r, as shown. \Vhen the plugs P and Pare at rest, the plates 0 and p at their lower ends rest upon metalplates q and close I the circuit between the wires 0 and b at.

and insulated therefrom, but moving with it,

its free end arranged to make contact with the stop 9 and its oppositeend connected by wire 2 with the contact-screw e. I arrange one of thesesockets A for each pair of plugs P and P and their wires or cords on theoperators table. The wire 0 of the plug P connects with thecontact-screw e, the wire 11 extending from said plug throughannunciator An to the binding-post r which is connected by wire I) withthe metal 19 of the plug P. The other plate 0 of the plugP con nects bywire 0 to binding-post 1- from which runs wire 0 to the spring f oflooping-in socket A. A wire 3 runs from the body d of the socket Athrough the telephones T and T to the part 70 of a double key K, and awire 7L extends also from the stop g to the back contact of the saidkey. A wire it connects the lower part 70 of the key K with the wire h,as shown. The key K is arranged to strike the two anvils n and n to loopin the generator Gen. From the wire 3 I run a wire 5' to ground througha resistance Rh for a purpose fully explained in the followingdescription of the operation of my improved circuits and apparatus.

If a substation desires to call the central station, the operation canbe performed in two ways: first, by means of the crank-mag neto S,depressing the key K forms a ground connection at the substation, and atthe same time turning the crank, sending a current over the line,through the annunciator and battery at the central office, causing itsdrop to fall, and going to ground through the bat tery Ba; or, secondly,by depressing the key K and utilizing the battery Ba at the centralotfice to cause the annunciator to fall.

YVhen the central-office operator wishes to test a line to ascertainwhether it is in use or not, the plug P (see Fig. 3) is inserted intothe looping-in socket A, thereby looping into circuit the telephone T,as the spring f leaves the screw-contact e and the spring f makescontact with the stop g, so that a local metallic circuit then existsfrom plate (1 of plug P wires 0 contact-screw 6, wire If, spring f, stopg, wire h, key in, wire 3, including telephone T, socket d, plug P,spring f, wire 0 plate (1 of plug P, wire I) and I), to plate q again.This circuit is now broken by the removal of the plug P from itsrest-plate q, the operator to test touching its terminal j to the metalsocket (Z of the line wanted.

The operator at the middle board, as shown in Fig. 7, has thus appliedthe tip of plug 1) to the test plate or tube d of the line which isbeing tested. \Vhen one of the pair of plugs is thus used for testing,it will be understood that the other plug of the pair will have beeninserted in the spring-jack switch of the calling-subscribers line inmaking the initial connection therewith. In Fig. 7, however, the plug 13is not shown thus inserted. It may be convenient at times to test aline, as shown, leaving the other plug of the pair in its socket, butordinarily connection is first made with the calling-subscribers linewith one plug, and the order being received for connection with anotherline the line thus wanted is tested. If the line is in use, there willbe no click in the operators telephone, as the battery Ba will have beenremoved from the line by the plug used to connect the line-termin alwith the one called. If the line is not in use, a click will be heard,as a circuit will have been formed from, via ground, battery Ba,conductor 0, stations M, N, conductor 19, socket d to plug Ph,continuing by wires 0 0*, spring f, plug P', socket metal d, wires 5 and3 through resistance Rh to ground. This resistance Rh is sufficient toprevent appreciable loss of voice-current, while affording a path toground for the testbattery.

The operators telephone being connected in metallic circuit could not beused in test ing for line, so I put in a ground branch 3 with resistanceRh sufficientin amount to prevent the annunciator An from being throwndown during the testing. The resistance Rh, besides serving to cut'downthe battery-eurrent to a strength insufficient to actuate theannunciatoigserves to preventthenoise in the operators telephone, due tothe presence of a ground on her metallic circuit. It is a wellknown factthat when a ground connection is extended from a metallictelephone-circuita path to ground is furnished for static chargesinduced upon the line, and that the eltect of such charges upon thetelephone is to cause a noise therein, and this noise may be diminishedor prevented by inserting in the ground connection a resistance. Havingfound the line free, and wishing to call the substation, the operatornext inserts the double plug P into the socket of the line, thusconnecting the operators local metallic circuit into the line metalliccircuit, as will be seen by tracing the course of the circuit, startingfrom plate 19 of the plug P, annular plug end Z, socket-frame d,by wireI) to substation through its bell S, returning by wire 0, spring f,partj of plug P to plate 0 of the plug. lhe local metallic circuithaving already been described need not be again traced.

In Fig. 6 the metallic telephone-circuit l) c is shown looped inmetallic circuit with the other telephone-line. When the plug P is firstinserted, the line Z) c is connected with operators telephone set,provided a plug P isinserted in the looping-in jack A, as shown in Fig.3. Now the final connection between the two lines is made by insertingthe corresponding plug 19 of the pair in the springjack loop-switch ofthe other telephone-line on the same board, or, as shown in Fig. 6, uponan adjoining board or section of the switchboard. In this manner the twotelephone-lines are looped together for conversation. The operator, tocall the attention of the called subscriber thus wanted, next depressesthe double key K, looping in the generator Gen, which may be amagneto-generator or any other source of electricity.

I have not made mention of the circuits and apparatus except as theyrelate to signaling and the necessary connections to effect that result;but it will of course be understood that the signaling-circuits aretalkingcircuits and that telephones will be used, although not so shownor described.

The double connecting-plug P may also be used to connect together thecentral-office terminals of two line-circuits, and in practice I so usethem.

In Fig. 5 I show, in connection with the operators looping-in socket, amodification in the manner of connecting the operating parts, theoperators instrument outfit being represented by the telephone T and asubstation B being shown without any of. the intervening apparatus. Inthis case the spring f, instead of making a part of the line, is used toconnect the telephones in. The wires 3 and z from a substation connect,after passing through the switchboard and double plugs, withcontact-screw e and spring f of the socket d, respectively, the wire 2being connected to the socket d, looping in the telephones andterminating with the tail of spring f, the stop 9 being connected withthe contact-screw e. WVhen the metallic plug P is not inserted in thejack, the circuit enters the spring-jack by the contact e, passingthence to the linespring f and to line again. WVhen the plug P isinserted the circuit may be traced from line to contact 6, thence tocontact-point e by wire thence to the upper spring f, through telephoneT to body d of switch, through metallic plug P to line-spring f, andthen to line.

It is obvious that the arrangement I have described admits of testing byother methods than the one I have described. For instance, one end of anindependent conductor may be applied to the frame of the spring-jack andthe other to the tongue of the operator, in which case the presence orabsence of the battery would be noted .by an electrolytic taste or bythe absence thereof; or I may provide a permanent electromagnetictesting device with a normally open terminal, such as a flexibleconductor terminated by a metal plug, which, when touched to the frameof any jack, will operate the testing device by means of theline-battery, if said line is not already in use.

I claim 1. In a multiple-switchboard telephone system, a metallicreturn-line circuit extending from a central station to a series ofsubstations and normally open at the said central stations; aspring-jack or contact socket therefor at each of a number of boards,the metal frames of said spring-jack being united to one wire of thesaid metallic line-circuit and the contacts of said jack insulated fromsaid frame being successively included in the circuit of the second lineof said circuit; a battery connected with the said second line betweenthe final spring-contact and the ground, a loop extension at the centralstation including a ring-off annunciator, and provided at each end witha double conductor-plug, whereby the said metallic line-circuit may beconnected with any other metallic circuit; and a testing or try signaldevice comprising an auxiliary spring-jack with a spring-contact formingpart of the loop extension, a groundbranch circuit connected to theframe thereof; a receiving-telephone and a resistance-coil or itsequivalent included in the said ground branch and a solid plug adaptedwhen inserted to bring said ground branch into contact with the loopextension in the manner and for the purposes specified.

2. The combination in a multiple telephoneswitchboard,of a pair ofdouble-contact or metallic-circuit connecting-plugs, a local loopcircuitincluding the said plugs, and a springcontact; a telephone ortelephones; a normally open extension of the said local loopcircuitincluding the said telephones; and a springjack socket and solid plugtherefor controlling the spring-contact of the loop-circuit and adaptedupon the insertion of the said plug in the said socket to open the saidspring-contact, and to close a second,whereby the normally opentelephone extension-circuit is made to form a part of the localloopcircuit, substantially as hereinbefore described and for the purposespecified.

3. In a multiple switchboard wherein each line entering the office isrepresented upon each board by a separate contact spring-jack, thehereinbefore-described looping-in device consisting of the doubleconductor-plugs, the metal ring seat therefor upon which the said plugsnormally rest and which serve to connect the two conductors in each plugtogether, so that when one is lifted the other maintains the continuityof the local circuit; a local loop-circuit extending by doubleconducting-cords from the two plugs; an auxiliary jack included in thesaid local circuit; a solid metal plug controlling the contacts thereof,a continuation of the said circuit controlled by the said auxiliary jackand plug and including the office-telephones; and a double keycontrolling the signaling appliances, as and for the purposes specified.

4. The combination in a multiple telephoneswitchboard adapted for theinterconnection of metallic line-circuits of a series of connectingsockets or spring-jacks, one for each line on every board; with adouble-wire connecting and signaling apparatus composing the followingelements, a local loop-line provided at each end with a double-conductorconnecting-plug, whereby the switchboard springjack of one line may beconnected with that of another line; an auxiliary spring-jack formingpart of the said loop-line; a solid metal plug adapted for insertiontherein; a normally open continuation loop-circuit includ ingtelephones, having its open terminals in and controlled by the auxiliaryspring-jack,

and a double key included in said continuation circuit; acalling-generator or equivalent source of energy in a secondcontinuation loop, adapted to be connected with the first by depressionof the said double key, all arranged and connected as described,wl1erebywhen one or both of the double plugs are in use, the office-telephonesmay be introduced or looped in by the insertion of the solid plug in theauxiliary jack, or signals may be transmitted by pressure of the keys,substantially as hereinbefore described.

5. The combination with a series of pairs of connecting cords and plugs,each provided with two conductors for the connection of metalliccircuits, of a local spring-jack and a solid plug for each pair, with acontinuation lo0p-circuit including telephones and signalsending keyscommon to the series and adapt ed to form a part of the circuit of anypair of cords and plug connectors through the local springjack thereofand upon the insertion of the plug of the said jack as described.

6. In a multiple-switchboard system for metallic circuits, thetry-circuit and testing apparatus consisting of the normally openmetallic line-circuit, a spring -jack on each board therefor, each jackhaving contacts serially connected in one side of the line-circuit, andhaving its insulated frame connected by a branch with the other side ofthe line-circuit, the battery normally connected with the contact sideof the line, the testingplug 1?, the auxiliary jack and the solid plugtherefor, a ground branch circuit including a receivingtelephone, and asuitable resistance, and a connecting-wire between the plug P and theauxiliary jack which by the insertion of the solid plug is brought intocontact with the telephone ground branch,whereby by inserting the solidplug and touching the frame of any of the line spring-jacks, it may beascertained by the presence or absence of a click caused by the batterywhether or not the line is in use or any other board.

7. A pair of loop-plugs having the corre? sponding terminals thereofconnected together by different strands of flexible cords, an ope 'ators metallic telephone-circuit adapted to be connected in circuit withsaid strands, and a ground connection from said operators metalliccircuit, containing a resistance adapted to prevent the disturbance ofthe 0perators telephone set by static discharges, substantially asdescribed.

8. A pair of loop-plugs having the corresponding terminals thereofconnected together by different strands of flexible eords,au operatorslocal metallic circuit including a telephone, a switching device adaptedto connect said local circuit in circuit with said strands, and aconnection to ground from said local circuit containing a resistanceadapted to prevent the disturbance of the operators telephone by staticdischarges, substantially as described.

9. In a telephone system, the combination with a telephone-line, of anormally-closed connection to ground at the central station containing abattery and a calling device, a grounded testing set adapted to beconnected with the line at any board, and a resistance included incircuit with said grounded testing set so adjusted relatively to thevol.- tage of said battery that said calling device remains unactuatedwhen circuit is closed through said grounded testing set, saidresistance being also adjusted to prevent the disturbance of theoperators telephone when on metallic circuit, due to static chargespassing to earth through said ground connection substantially asdescribed.

10. In a telephone system, the combination with a telephone-line, of anormally-closed connection to ground at the central station containing atesting-battery, an operators metallic circuit containing her telephoneset, a ground connection from said metallic circuit, whereby saidoperators telephone may be included in circuit with saidtcsting-battery,and a resistance included in said ground connectionadapted to prevent the disturbance of the operators telephone when onmetallic circuit due to static charges passing to earth through saidground connection, substantially as described.

In witness whercof I hereunto subscribe my name this 7th day ofNovember, A. 13.1887.

JOHN J. CARTY.

\Vitnesses:

CHARLES A. TERRY, DANL. W. Eoenconn.

